1. Field of the Invention
The present invention generally relates to consumer electronics and, more particularly, relates to TV and audio technology.
2. Description of Related Art
With regard to existing circuits requiring positive and negative symmetrical dual power supply, what are the most commonly seen are OCL audio power amplifying and color TV field scanning circuits. These OCL power amplifying circuits without output coupling capacitors have greater failure rate and hazard than those OCL power amplifying circuits with output coupling capacitors. This is because when the OTL power amplifying circuits are damaged, the blocking coupling capacitors can protect other loads from being easily burned. When the OCL circuits are damaged, not only can the last stage loads be easily burned, but also other failures will be extended jointly. Such other failures include the burns of sound boxes, video tube necks and transformers. Therefore, a protection circuit is needed to protect the OCL circuits against abnormality.
Some existing OCL circuits, especially the color TV field output circuits, have been equipped with additional protection measures against the abnormality. However, the circuit can be very complicated. In addition, the existing technology is effective to only one of the load short-circuits when the loads of positive and negative dual power are subject to imbalance. Namely, it is only effective to the load short-circuit of positive power or the load short-circuit of negative power and ineffective to the simultaneous short-circuit of loads of both the positive and negative power or other abnormalities of balance symmetry. For OCL circuit abnormalities, in the majority of cases, the original power integrated device is in good condition, but its external elements cause abnormal overload, which then causes damage to the power integrated device, and further leads to other failures, such as, for example, the burns of the sound boxes and video tubes. However, the existing technology fails to provide a solution to protect the power integrated module in time and prevent it and the last stage loads from being burned before the power integrated module is damaged in the event that the abnormal state occurs.
Therefore, it is desired to provide a timely and effective protection over the circuit before the power integrated device IC is damaged in the event that the external elements of the power integrated device IC causes an abnormal state.